Microscopic observation of atherosclerotic lesions reveals that both focal extracellular and selective intracellular lipid deposition occur. While some smooth muscle cells within atherosclerotic lesions contain substantial lipid, others are essentially lipid free. The reasons for the focal nature of extracellular lipid deposition and restricted accumulation of lipid by certain cells is not known. This project will assess the importance of cell injury and cell proliferation as localizing factors in the focal deposition of cholesterol within atherosclerotic lesions.